A Trial in Painful Diabetic Peripheral Neuropathy With GRT3983Y

• Change From Baseline in the Mean of the Daily Average Pain Intensity Scores (on an 11-point NRS) Over the Entire 12-week Maintenance [ Time Frame: Baseline, Daily scores over entire 12 week maintenance ] [ Designated as safety issue: No ]
• Proportion of Subjects Achieving Various Levels of Pain Improvement (Including 30% and 50%) Based on the Percent Change From Baseline to the Last 7 Days of the 12-week Maintenance on an 11-point NRS (Responder Analysis). [ Time Frame: Baseline, Last 7 days of 12-week maintenance ] [ Designated as safety issue: No ]
• Change From Baseline in the Mean of the Daily Average Pain Intensity Scores (on an 11-point NRS) Over Each Week of Maintenance. [ Time Frame: Baseline; daily scores over each week of maintenance ] [ Designated as safety issue: No ]
• Change From Baseline of the Weekly Mean of Night Pain Intensity (on an 11-point NRS). [ Time Frame: Baseline; weekly mean ] [ Designated as safety issue: No ]
• Change From Baseline of the Weekly Mean of Current Pain Intensity (on an 11-point NRS) in the Evening and in the Morning, Respectively. [ Time Frame: Baseline, weekly mean ] [ Designated as safety issue: No ]
• Brief Pain Inventory Scores: Changes From Baseline to Day 8, Day 15, Day 22, Day 29, Day 43, Day 57, Day 71, Day 85, Day 99, and Day 113 (Final Visit). [ Time Frame: Baseline, weekly mean ] [ Designated as safety issue: No ]
• Neuropathic Pain Symptoms Inventory: Changes From Baseline to Day 8, Day 15, Day 22, Day 29, Day 43, Day 57, Day 71, Day 85, Day 99 and Day 113 (Final Visit) [ Time Frame: Baseline, weekly mean ] [ Designated as safety issue: No ]
• Patient Global Impression of Change Using a 7-point Verbal Rating Scale, on Day 29, Day 71 and Day 113 (Final Visit). [ Time Frame: Day 29, Day 71 and Day 113. ] [ Designated as safety issue: No ]
• Short Form 36 Health Survey (SF-36®): Changes From Baseline to Day 29, Day 71 and Day 113 (Final Visit). [ Time Frame: Baseline, Day 29, Day 71 and Day 113. ] [ Designated as safety issue: No ]
• EuroQol-5 Dimension Health Questionnaire: Changes From Baseline to Day 29, Day 71 and Day 113 (Final Visit). [ Time Frame: Baseline, Day 29, Day 71 and Day 113. ] [ Designated as safety issue: No ]
• Assessment of Each Item of the Leeds Sleep Evaluation Questionnaire: Changes From Baseline to Day 29, Day 71 and Day 113 (Final Visit). [ Time Frame: Baseline, Day 29, Day 71 and Day 113. ] [ Designated as safety issue: No ]
• Hospital Anxiety and Depression Scale: Changes From Baseline to Day 29, Day 71 and Day 113 (Final Visit). [ Time Frame: Baseline, Day 29, Day 71 and Day 113. ] [ Designated as safety issue: No ]
• Time to Treatment Discontinuation Due to Lack of Efficacy. [ Time Frame: Baseline to time to treatment discontinuation ] [ Designated as safety issue: No ]
• Assessment of Rescue Medication Usage During the 4-week Titration. [ Time Frame: 4-week titration phase ] [ Designated as safety issue: No ]

• Quality of life [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
• Responder (30% and 50% pain reduction) [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
• Adverse events [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]

This trial is assessing the analgesic efficacy and safety of a new central analgesic in subjects with pain due to diabetic peripheral neuropathy (DPN).

• Drug: GRT3938Y
  Overencapsulated tablets of GRT3983Y, 100 to 300mg daily dose, 16 weeks treatment.
• Drug: Placebo
  Overencapsulated tablets of placebo, 16 weeks treatment.

• Experimental: A GRT3983Y
  Participants randomly assigned to receive GRT3983Y.
  Intervention: Drug: GRT3938Y
• Placebo Comparator: B Placebo
  Participants randomly assigned to placebo.
  Intervention: Drug: Placebo

Inclusion Criteria:

• Symmetrical painful diabetic peripheral neuropathy

Exclusion Criteria:

• History of hypersensitivity, allergy or contraindication to opioids and acetaminophen
• Confounding painful conditions
• Significant vascular disease
• History or risk of seizure
• Chronic disease that might effect drug absorption, distribution, metabolism, or excretion
• Female subjects who are being pregnant or breastfeeding
• Evidence or history of alcohol, medication, or drug abuse